The present invention relates to 16-benzalandrosta-1,4-diene-3,17-dione compounds which can be used in components for optical higher harmonic wave generation, electro-optical switching, and the like, a process for producing the compounds, and non-linear optical materials and non-linear optical components which use the same.
Non-linear optical materials, which are expected to play an important role in optical communication technology, exhibit such functions as optical mixing, parametric oscillation, optical higher harmonic wave generation and the like based on the non-linear optical susceptibility of the materials. Previously, inorganic crystals of KH.sub.2 PO.sub.4, NH.sub.4 H.sub.2 PO.sub.4 or the like have been used as said materials. These materials, however, have been unsatisfactory for meeting the requirements of the above-mentioned applications because of their deliquescence, low non-linear susceptibility and low damage threshold value.
Furthermore, since the first order and second order electro-optical effects, which can be used for optical switching, respectively arise from essentially the same non-linear polarization as that which gives rise to the second order and third order non-linear optical effects, the same material might be used to obtain the two kinds of effects. However, inorganic materials have a drawback of a relatively longer response time.
Organic non-linear optical materials, which make use of the polarization of their .pi.-electron system, have a higher non-linear optical coefficient, no deliquescence in general and higher damage threshold value as compared with inorganic materials. Therefore, the research and development thereof is being actively forwarded in various fields. Recent results of such research and development are described in detail, for example, in Nonlinear Optical Properties of Organic Molecules and Crystals, Vols. 1 and 2, edited by D. S. Chemla and J. Zyss (published by Academic Press, 1978).
However, no material has ever been found which has a sufficiently high non-linear optical coefficient to attain the intended purpose even in the case of low output lasers such as semiconductor lasers. Accordingly, further development of a novel non-linear optical material is eagerly awaited.